Seal

ABSTRACT

A liquid propellant gun is provided with a seal and a multi diametered chamber which centripetally deflects the seal to generate a preseating force thereon.

nited States Patent 1191 Ashley Jan. 8, 1974 [54] SEAL 1,376,130 4 1921 Asbury 89/26 539,733 5/1895 Gerdom 89/26 [75] Inventor Eugene Ashley Burlmgton 3,006,254 10/1961 Thierry 89/26 [73] Assignee: General Electric Company,

Burlington, Vt FOREIGN PATENTS OR APPLICATIONS [22] Filed, Feb v 1972 1,096,697 1/1961 Germany 277/212 C 21 App]. No.1 223,643

US. Cl 89/7, 89/26, 277/212 C Primary Examiner-Stephen C Bentley Attorney-Bailin L. Kuch et al.

[52] [51] Int. Cl. F4lf [58] Field of Search 89/7, 26;

102/1310. 1; 285/110; 92/240, 245, 246; [57] ABSTRACT 277/212 236 A liquid propellant gun is provided with a seal and a multi diametered chamber which centripetally deflects [56] References and the seal to generate a preseating force thereon.

UNITED STATES PATENTS 2,117,885 5/1938 Hasck 89/26 3 Claims, 4 Drawing Figures 32 F 50 EM K 1(\ -l ZO D Dc.

7639mm? S-cr/o/v SEAL BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a centripetally preloaded, annular seal for combustion apparatus, especially adapted to use in a liquid propellant gun. The invention 7 herein described was made in the course of or under a contract or subcontract thereunder with the Department of the Navy.

2. Prior Art Annular breech seals are shown in US. Pat. Nos. 3,114,290; 3,354,780; and 3,403,596, suitable for con- 'ventional guns firing caseless ammunition. A liquid propellant gun which is well adapted to utilize the seal of the present invention is shown in US. Pat. application Ser. No. 148,833, filed June 1, 1971 by DR Tassie, to which reference may be had for details of the total system not herein shown.

SUMMARY OF THE INVENTION BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic in longitudinal cross section of a prior art firing chamber, such as is shown in Ser. No. 148,833 supra;

FIG. 2 is a schematic in longitudinal cross section of a seal embodying this invention;

FIG. 3 is a schematic in longitudinal cross-section of a multi diametered firing chamber and seal embodying this invention; and

FIG. 4 is a detail view in longitudinal cross-section of a gun embodying this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In guns firing conventional cased ammunition, the interface between the combustion chamber and the gun bolt is sealed by the cartridge case.

In the prior art guns, as shown in FIG. 1, utilizing liquid propellant and a projectile without a cartridge case, the interface between the combustion chamber 12 and the gun bolt 14 is closed by a seal 16 which is carried bythe bolt and has a slight clearance with respect to the wall of the chamber. This allows the seal to be easily inserted into the chamber during the loading operation. After firing, as the combustion gases are developed in the chamber and the gas pressure rises, a small flow of gas develops past the periphery of the sea]. This flow induces a pressure differential between the stagnant gas within the chamber and the flowing gas without the chamber. The higher pressure within the chamber causes the seal to expand centrifugally until it abuts the chamber wall and obstructs further gas flow. From this condition on, the seal is self-energizing in that a higher gas pressure within the chamber tends to seat the seal yet more firmly. The disadvantage of such conventional seals is that the small initial leakage causes heating and erosion of the seal, and often allows foreign particles to enter the gap and to interfere with the seating of the seal.

The combination of the seal and the firing chamber shown in FIGS. 2 and 3 provides a full seating of the seal with both the chamber and the gun bolt before firing.

The seal 20 is shown in its free state in FIG. 2, and is transversely annular, with a substantially triangular longitudinal crosssection. The seals outer annular surface 22 has a small positive taper forward the front, shown as angle PT, its aft transverse surface 24 may be slightly conical internally, shown as angle NT, and its hypotenuse may be concave. If the seal is subjected to an annular, centripetal force on its forward edge annulus 26, a compound deflection will occur which pivots the longitudinal cross section about a transverse annular axis, so that the major diameter D of the forward edge-annulus is reduced, reducing the angle PT, and the aft transverse surface 24 becomes less conical, increasing the angle NT.

The chamber 30 has an internal diameter D, with a tapered aft entrance or lead-in portion 32 having an initial aft internal diameter D greater than D and a forward internal diameter equal to D FIG. 3 shows the seal 20 in its free state. As the seal advances through the lead-in portion towards the firing portion the forward edge annulus 26 engages the wall 32 and is progressively deflected by the peripheral force F, to reduce its major diameter D,. When the forward edge annulus 26 enters the firing section as at 20", the peripheral force F" plateaus at a maximum, while the major diameter D plateaus at a minimum which is the diameter of the firing chamber D with the forward edge annulus firmly seated against the chamber wall. As a result of the compound deflection, the aft inner edge annulus 28 of the seal will be firmly seated against the face 34 of the bolt 36. Thus the preseating of the forward edge 26 against the chamber wall and the preseating of the inner edge 28 against the bolt face will preclude the flow of gas or particles past the seal, and any resultant erosion.

After firing, as the gas pressure builds up, the aft outer edge annulus 29 of the seal will expand, until the outer annular surface 22 contacts the chamber wall along its full length, with the seal minor diameter D also equal to Dc, and the aft face 24 contacting the bolt face 34 along its full length. Thereafter, under increased gas pressure, the seal and the chamber will expand together. After discharge, the seals elasticity will cause it to return to the condition of 20".

In a gun embodiment, a barrel 50 having a chamber 52 similar to 30/32 is locked into a receiver 54. A bolt 56 reciprocates in the chamber and carries a chamber seal 58, similar to 20, which is held by a retainer 60 and a resilient washer 62. The aft end of the retainer is threaded at 64 into a bore 66 in the bolt. An electrode 68 is fixed in a bore 70 through the retainer and bolt by an insulator 72 and a wedge 74. As the bolt advances into the chamber entrance 32 the seal 58 is distorted by the chamber wall and preseated thereagainst as described with respect to FIG. 3.

What is claimed is:

l. A combustion apparatus comprising:

a vessel having a substantially cylindrical chamber therein,

said chamber having an internal wall having an aft gressively reduced thereby, providing a continuous edge sealing between said seal and said wall; and

said piston has a forward facing transverse surface aft of and adjacent to said seal;

said aft, annular, approximately transverse face of said seal having an inner annular edge which in the free state of said seal is longitudinally forward of a piston for obturating said forward portion of said chamber,

said piston having a resilient, integral, annular seal mounted thereon,

said seal being transversely annular, with substantially triangular longitudinal cross-section, having an outer annular, approximately cylindrical face and an aft, annular, approximately transverse face,

the remainder of said aft face,

whereby, as said external diameter of said forwardmost annular edge of said seal is progressively reduced, said inner annular edge is displaced progressively longitudinally aft, and said inner annular edge, and only said inner annular edge engages said forward facing transverse surface, providing a continuous edge sealing between said seal and said sursaid outer face having a forward-most annular face I edge, which in the free state of said seal is Combustlon apparatus accordmg to clam 1 w erem:

greater in external diameter than the remainder of said outer face, and which in the free state is less than said initial internal diameter of said chamber and greater than said final internal diameter of said chamber; forward firing P whereby, as said piston is advanced longitudinally A Combustion apparatus according to Claim 1 forwardly through said entrance portion of said Wheraini chamber, said forward-most annular edge of said Said apparatus is a g seal and only said forward-most annular edge ensaid vessel is a gun barrel; and

gages said wall of said chamber, and the external said piston is a gun bolt.

diameter of said forward-most annular edge is prosaid chamber aft entrance portion has a negative taper from its aft initial diameter to said final diameter, said final diameter, being the diameter of said 

1. A combustion apparatus comprising: a vessel having a substantially cylindrical chamber therein, said chamber having an internal wall having an aft entrance portion merging into a forward firing portion, said aft entrance portion having an aft, initial, internal diameter and a forward, final diameter, said initial diameter being greater than said final diameter; a piston for obturating said forward portion of said chamber, said piston having a resilient, integral, annular seal mounted thereon, said seal being transversely annular, with substantially triangular longitudinal cross-section, having an outer annular, approximately cylindrical face and an aft, annular, approximately transverse face, said outer face having a forward-most annular edge, which in the free state of said seal is greater in external diameter than the remaInder of said outer face, and which in the free state is less than said initial internal diameter of said chamber and greater than said final internal diameter of said chamber; whereby, as said piston is advanced longitudinally forwardly through said entrance portion of said chamber, said forwardmost annular edge of said seal and only said forward-most annular edge engages said wall of said chamber, and the external diameter of said forward-most annular edge is progressively reduced thereby, providing a continuous edge sealing between said seal and said wall; and said piston has a forward facing transverse surface aft of and adjacent to said seal; said aft, annular, approximately transverse face of said seal having an inner annular edge which in the free state of said seal is longitudinally forward of the remainder of said aft face, whereby, as said external diameter of said forward-most annular edge of said seal is progressively reduced, said inner annular edge is displaced progressively longitudinally aft, and said inner annular edge, and only said inner annular edge engages said forward facing transverse surface, providing a continuous edge sealing between said seal and said surface.
 2. A combustion apparatus according to claim 1 wherein: said chamber aft entrance portion has a negative taper from its aft initial diameter to said final diameter, said final diameter, being the diameter of said forward firing portion.
 3. A combustion apparatus according to claim 1 wherein: said apparatus is a gun; said vessel is a gun barrel; and said piston is a gun bolt. 